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Essential Evidence is a powerful, one-stop, state-of-the-art reference that includes best-evidence answers to your most important clinical questions concerning symptoms, diseases, and treatment. Its concise, highly structured content is tightly integrated and hyperlinked to thousands of calculators, articles, and evidence summaries within Essential Evidence Plus to make searching for answers quick and seamless. Each topic has a “strength of evidence” rating for every recommendation, a “Bottom-line” summary that introduces each section, and a broad array of helpful algorithms.

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Air embolismEssential Evidence Topics, 12-Oct-2017Overall Bottom Line: Diagnosis of arterial gas embolism is based on clinical history, with support from quantitative electroencephalography (EEG), computed tomography (CT), and magnetic resonance imaging (MRI). The patient should be given supplemental

Alcohol intoxication and poisoningEssential Evidence Topics, 28-Mar-2017Overall Bottom Line: Diagnosis of alcohol intoxication is made by history and physical examination. A positive blood alcohol concentration (BAC) is helpful to secure the diagnosis but does not correlate with the degree of intoxication. Patients with i

Allergic rhinitisEssential Evidence Topics, 9-Jul-2015Overall Bottom Line:
Empiric treatment of patients with classic symptoms is appropriate.
Treatment with intranasal steroids and nonsedating antihistamines is sufficient for most patients.
Intranasal steroids are also effective in treating ocular

Alopecia and baldnessEssential Evidence Topics, 10-Sep-2017Overall Bottom Line: Diagnosis is based on history and physical findings; in unclear cases, a skin biopsy may be useful. Minoxidil 5% topical solution (preferred initial therapy) and finasteride (FDA approved for men only) are treatment options for an

Alpha-1 Antitrypsin DeficiencyEssential Evidence Topics, 7-Jun-2017Overall Bottom Line: Population screening for alpha-1 antitrypsin (AAT) deficiency is not generally recommended. AAT levels should be checked in patients when there is a high degree of suspicion (); if abnormal, confirm by genetic testing. Consider

Altitude sicknessEssential Evidence Topics, 28-Dec-2017Overall Bottom Line: Acute mountain sickness (AMS) is defined as the presence of headache in an unacclimatized person who has recently arrived at an altitude of 2500 m (8202 ft), plus the presence of one or more of the following: GI symptoms (anorexia, n

AmenorrheaEssential Evidence Topics, 12-Oct-2017Overall Bottom Line: Women should be evaluated for a cause of amenorrhea if they have not started menarche by the age of 15 years. Women with a history of regular menses should be evaluated for a cause of amenorrhea if they have missed 3 cycles. Ev

AnaphylaxisEssential Evidence Topics, 30-Jul-2017Overall Bottom Line: The diagnosis of anaphylaxis is made clinically. Attend first to airway, breathing, and circulation. Epinephrine and oxygen are the most important interventions. Laboratory tests may help confirm a diagnosis of anaphylaxis.

Anemia (megaloblastic)Essential Evidence Topics, 22-Jan-2018Overall Bottom Line: In patients with symptoms suggestive of anemia and macrocytosis, order B12 and folate levels. If B12 is indeterminate, order methylmalonic acid and homocysteine levels. Oral folate or oral or intramuscular (IM) B12 supplementat

Aneurysm (abdominal aorta)Essential Evidence Topics, 2-Mar-2017Overall Bottom Line: One-time screening for abdominal aortic aneurysm is recommended in men between the ages of 65 and 75 years who have ever smoked ( ) and may also be useful in nonsmoking men in that age range. There is insufficent evidence to recommen

Aneurysm (cerebral)Essential Evidence Topics, 30-Jul-2017Overall Bottom Line: Screen for cerebral aneurysm with MRA if 2 first-degree relatives have an intracranial aneurysm and in patients with autosomal dominant polycystic kidney disease. A cerebral aneurysm of 7 mm or less has a 5-year risk of rupture of

Aneurysm (thoracic aorta)Essential Evidence Topics, 18-Nov-2017Background: OVERALL BOTTOM LINE Most patients are asymptomatic, but patients may complain of midback pain or chest pain. Transthoracic echocardiography (TTE) is indicated in patients with an enlarged aortic root to assess the severity of aortic dilata